Method of governing internal-combustion engines.



T. RIGBY. METHOD OF GOVERNING INTERNAL COMBUSTION ENGINES.

APPLICATION FILED OOT.16, 1911.

Patented Feb. 13, 1912.

12200221507." Thomas R195 COLUMBIA PLANOGRAPH CO..WASH1NGTON, u. c.

I fltior /ze y UNITED STATES PATENT. OFFICE.

THOMAS -RIG'BY, OF DUMFLR IES, SCOTLAND.

METHOD OF GOVERNING INTERNAL-COMBUSTION ENGINES.

To all whom it may concern:

Be it known that I, THOMAS RIGBY, of Station Hotel, Dumfries, Scotland,a subject of the King of Great Britain and Ireland, have inventedcertain new and useful Improvements in Methods for GoverningInternal-Combustion Engines, of which the following is a specification.

This invention relates to improvements in internal combustion enginesand is mainly intended to be used in connection with those enginesworking on the single acting Otto cycle in which an extra charge ofcombustible gas, or air, or a mixture of both is admitted to the workingcylinder in addition to the ordinary working charge drawn in during thesuction stroke.

The type of engine to which the invention is particularly applicable, isthat illustrated in the accompanying drawing and which is known as thevertical tandem type of engine (single acting Otto cycle) in which theupper cylinder is supported by the top of the lower cylinder in such amanner that there is a clearance space between the upper piston at theend of the down stroke and the cover of the lower cylinder, which spacemay be used for compressing and supplying additional gaseous fluid toeither working cylinder by the displacement of the upper piston. Thegaseous fluid is admitted to the clearance space in any suitable manner,but preferably by way of a back pressure valve which closesautomatically at the commencement of the down stroke of the coupledpistons compressing the gaseous fluid in the clearance space to thenecessary pressure prior to its admission to a working cylinder orreceiver. In such an engine the compressed gaseous fluid if delivereddirect is preferably admitted once every revolution to either cylinderalternately and preferably only for the purposes of carrying overload.

With such engines as those hereinbefore referred to, there may beexpected to be a little cooling of the additional gaseous fluid (whichis heated by the compression) before it is admitted to the workingcylinder, but this is chiefly owing to radiation losses.

The present invention consists in a meth- 0d of working and governinginternal combustion engines in which additional gaseous fluid isadmitted to the working cylinder at or near the end of the suctionstroke and is preferably cooled by water prior to its Specification ofLetters Patent.

Application filed October 16, 1911.

Patented Feb. 13, 1912.

Serial No. 654,941.

admission to the working cylinder to a temperature below the suctiontemperature usual in engines working on the Otto cycle.

The cooling may be eflected by bringing the water or other coolingmedium into direct contact with the heated gases or the heated gasesinto contact with water cooled surfaces, preferably the additionalgaseous fluid being cooled to as near the temperature of the atmosphereor to the temperature of the cooling water as possible prior to itsadmission to the working cylinder.

According to the invention the cooling required is in practiceconsiderable, and large surfaces are required to effect it; it isessential that the additional working fluid should be cooled below thetemperature of the ordinary charge and admitted at or near the end ofthe suction stroke, and engines in which but slight cooling of the addedcharge takes place form no part of this invention.

The temperature of the working charge in the cylinder of an ordinaryinternal combustion engine, before compression commences, has a greatinfluence on the Working temperatures, both at compression andthroughout the combustion or power stroke. For instance, in an ordinaryOtto cycle engine, the suction temperature at the end of the suctionstroke is seldom less than eighty degrees centigrade and often rises toover one hundred degrees centigrade.

If additional gaseous fluid at atmospheric temperature or thereabout isadded to the working charge the effect of such addition is to reduce thetemperature of the charge before the return of the piston on thecompression stroke. For instance, if half the weight of the ordinaryworking charge is added in the form of additional gaseous fluid atatmospheric temperature to the working charge, having at the time asuction temperature of eighty degrees centigrade, the efl ect will be toraise the pressure in the cylinder to approximately half an atmosphereabove that of the atmosphere while the temperature of the -mixture Willbe less than the original eighty degrees centigrade. The direct resultof this reduction of temperature and increase of pressure before theactual compression stroke has commenced, is to reduce the maximumtemperature of combustion to a much lower temperature, say to theneighborhood of one thousand two hundred to one thousand three hundreddegrees centigrade, instead of the usual much higher temperature,without in any way reducing the percentage of combustible present in thefinal mixture prior to ignition and combustion. In consequence the heatlosses in the water jacket of a working cylinder are considerablyreduced and a heat gain is effected which is much greater than the heatdissipated by cooling the additional gaseous fluidbefore it is admittedto the working cylinder.

It is obvious that if additional cooled gaseous fluid be not added tothe working cylinder of an engine of the type indicated the maximumtemperature of combustion will be far higher than the maximumhereinbefore indicated, namely one thousand two hundred to one thousandthree hundred degrees centigrade or thereabout, and as below a certainload it is not economical to introduce the additional cooled gaseousfluid, it is therefore preferable that the additional cooled gaseousfluid shall only be admitted to a working cylinder when the load is ator above a predetermined portion of the maximum load, and the amount ofgaseous fluid admitted is governed in accordance with the load up to themaximum load with maximum delivery of additional gaseous fluid atmaximum load, no additional cooled gaseous fluid being admitted whenworking below the predetermined load.

The governing of the engine is preferably on the throttle system but notnecessarily so, and the predetermined point above referred to is usuallyarranged to be somewhat below the full load of an ordinary engine(without addition of gaseous fluid) so that the maximum temperature ofcombustion at the predetermined point will not exceed the maximumtemperature of combustion obtained at the maximum load with maximumaddition of cooled gaseous fluid.

When air only is delivered as the addi tional charge, it is preferableto admit it at or above a predetermined load corresponding to themaximum temperature de sired as hereinbefore described, but at the timeadditional air is admitted the proportion of air may be automaticallyreduced and the proportion of gas increased in the 7 charge drawn intothe working cylinder unduly diluted by excess of air.

during the suction stroke to such an extent that although air underpressure is admitted to theworking cylinder, the final mixture beforeignition of the charge is not In all cases where air alone is admitted,the added air is cooled in the manner above described before itsadmission to the working cylinder.

In some cases, the point at which the additional cooled gaseous fluid isadmitted to the working cylinder corresponds to the full load of theengine (without any addition of gaseous fluid), a mixture weak incombustible being drawn into the working cylinder during the ordinarysuction stroke to give a maximum temperature of combustion not higherthan that desired atmaximum load with maximum addition of cooled gaseousfluid. In such a case it is preferable that the added cooled gaseousfluid (when a mixture of gas and air) shall be richer in gas than usual,so that the final mixture at maximum load before ignition will be'of thefull strength required. Any suitable mechanism or valve gear may be usedto effect this purpose.

When the additional cooled gaseous fluid is gas, the point at which itis admitted preferably corresponds to the full load of the engine(without addition of gaseous fluid) a weak mixture of gas and air beingdrawn into the working cylinder during the ordinary suction stroke ofthe engine. The ordinary gas supply is preferably in such a caseautomatically reduced to correspond with the addition of cooled gaseousfluid to the working charge the mixture being thus altered to the rightproportions to insure full strength of the final mixture at maximum loadbefore ignition and combustion takes place. When the additional cooledgaseous fluid is air and a weak mixture is used at full load(without-addition of cooled air) the proportions of gas and air drawn induring the ordinary suction stroke are automatically altered and theproportions of gas increased to insure full strength of the finalmixture before ignition and combustion at maximum load.

Any suitable mechanism or gear may be employed to effect the abovementioned alterations of the mixture to enable the engine to givemaximum power at maximum load if desired in all cases.

The invention may be applied to any Otto type engine in which theadditional gas or air or mixture of gas and air is obtained by using thedisplacement of the opposite side to the combustion side of a workingpiston to pump the gaseous fluid into a working cylinder or more thanone working cylinder and any modification maybe used of the system ofemploying this displacement of the piston or any projection thereof inany desirable manner either passing the cooled gaseous fluid direct tothe working cylinders or by way of a receiver or receivers.

Any of the above mentioned methods of sustaining a maximum load may beemployed in this cycle.

The accompanying drawing is a sectional elevation of a vertical tandemtwo cylinder internal combustion engine, working on the Otto cycle.

In this View, a and b designate the two working cylinders arrangedtandem; 0 0 their respective pistons; (Z the common piston rod uponwhich the two pistons are mounted; p a rod connecting the piston rod 0to the crankshaft (not shown); a the compression space formed by closingin the end of the cylinder (4, e e the gas or combustible mixtureadmission valves, w a throttle controlled by the governor, and f 7' theexhaust valves of the two working cylinders; the delivery valvecontrolling the pipe h leading from the compression space a in theworking cylinder 64 to the receiver 2', i an arrangement of coolingtubes placed within the receiver and cooled by water or other liquidsupplied through pipes i and caused to circulate around the outside ofthe tubes 2", the heated water passing away through the pipes 2' j jpipes leading from the receiver to the cylinders a Z) and controlled byextra admission valves 7c is operated by connections 7: from the sideshaft 9, m m the gas and air supply pipes; at the gas, or gas and air,governing valve, and 01 the connecting rod to the governor forcontrolling the valve and the supply of gas, or gas and air, to thecompression space a of the working cylinder; and g the side shaft withtwo cams g thereon which operate through connecting rods and links thevalves is and with two cams g which operate the exhaust valves Havingthus described my invention what I claim is 1. A method of governinginternal combustion engines in which the main charge is drawn in on thesuction stroke, which consists in admitting to the working cylinder ator near the end of the suction stroke,

a supplementary charge cooled to a temperature below the temperature ofthe charge, and in varying the amount of the supplementary charge inaccordance with the load.

2. A method of governing internal combustion engines in which the maincharge is drawn in on the suction stroke, which consists in admitting tothe working cylinder at or near the end of the suction stroke, asupplementary charge cooled to a temperature below the temperature ofthe charge, and in varying the amount of the supplementary charge inaccordance with the load, and in throttling the charge of the suctionstroke when the load is below a predetermined amount.

3. The method of governing internal combustion engines in which the maincharge is drawn in on the suction stroke, which consists, above apredetermined load, in admitting a supplementary fuel charge to acompressor from which it passes to the engine at or near the end of thesuction stroke, and varying said supplementary charge in accordance withthe load, and cutting off said supplementary charge from the compressorwhile below said predetermined load.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

THOMAS RIGB Y.

WVitnesses BERTRAM H. MATTHEWS, H. D. JAMESON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. C. I

